三峡升船机塔柱横梁混凝土施工技术

三峡升船机船厢室段塔柱承重结构的横梁混凝土浇筑施工难度大、复杂性高、无成熟技术可供参考。本文结合三峡升船机塔柱横梁混凝土浇筑的结构特点以及施工特性,总结了三峡升船机续建工程顶部横梁混凝土的施工技术,即采用分层、分块浇筑的办法,通过科学计算后进行合理的施工机械布置和浇筑施工管理,以保证塔柱横梁混凝土的施工质量。通过对贝雷架支撑系统的监测结果分析可知,贝雷架支撑系统的应力变形、挠度变形以及排架变形均满足施工承载要求,筒体位移亦满足技术要求,贝雷架支撑系统稳定、安全。三峡升船机塔柱横梁混凝土施工实践证明了本技术方案的有效性与可靠性,亦可为类似工程的施工组织设计与现场实施工作提供一定的参考。     

三峡升船机横梁支撑系统安全监测及分析

本文从监测对象的选择、监测项目的确定、监测点的布置以及监测结果的评价等方面详细介绍了三峡升船机横梁支撑系统的安全监测情况。监测项目包括:贝雷架支撑系统在混凝土浇筑前后以及混凝土浇筑过程中的应力、应变和位移监测;相应的塔柱混凝土墙体结构变形监测;横梁排架的立杆垂直度和位移监测。通过监测结果与原型荷载试验中获取的基础数据的比较分析表明:在施工过程中,横梁混凝土支撑体系安全可靠,应力、应变和位移等监测指标均满足设计要求,能够保证横梁混凝土的顺利浇筑。同时,本工程在安全监测方面建立的方案与技术体系可为其他同类工程的安全监测提供参考和借鉴。     

三峡升船机贝雷架安装与拆除技术

三峡升船机塔柱横梁贝雷架支撑体系的安装与拆除属于高空立体交叉作业,而且施工场地狭窄、施工强度大,贝雷架的安装与拆除所受到的施工干扰大,是三峡升船机塔柱施工中的难题之一。本文通过对贝雷架施工作业环境的系统分析,根据不同部位的特点与要求,制定了有针对性的包括施工设备布置、吊装单元划分、吊点设置、各部位拆除方案在内的塔柱横梁贝雷架安装及拆除施工技术体系。该技术体系在三峡升船机贝雷架安装及拆除工程中得到顺利实施,塔柱横梁贝雷架支撑系统的施工进度、施工成本及施工安全均实现了良好的效果,表明该技术方案合理可靠。本文中贝雷架的安装与拆除施工技术体系可为类似条件下的贝雷架安装和拆除施工提供参考借鉴。     

三峡升船机塔柱施工技术

本文介绍了塔柱结构的整体施工程序,并详细分析了土建结构精度控制、金属结构及其埋件精度控制、混凝土温控防裂和安全控制等几个方面的施工重点与难点问题。同时,就塔柱结构在施工过程中采用的施工测量控制技术、薄壁混凝土温控防裂施工技术、高精混凝土连续快速施工技术、金属结构埋件施工技术、高空大跨度横梁结构施工技术等进行了系统的总结。上述施工技术的应用,不仅满足了塔柱高精度的施工要求,保证了塔柱施工的顺利进行,同时也为类似的高精混凝土的施工打下了坚实的基础。     

三峡升船机横梁贝雷架支撑系统荷载试验

在三峡升船机续建工程中,针对塔柱横梁施工支撑体系复杂的特点,在横梁混凝土浇筑前进行荷载试验。试验选取轴1、轴2横梁及其相应的基础梁贝雷架作为模型,按照1∶1进行荷载原型试验,通过布置监测点以及采用合理的检测频率,完成试验数据的采集与分析。本次试验取得以下成果：得出了各类型杆件在加载过程中的最大应力值;随着加载量的增加,横梁、基础梁贝雷架的挠度变化量慢慢增大,模板及排架立杆高程在下降;随着加载量的增加,横梁、基础梁贝雷架都发生了较小的侧向位移,轴2横梁模板左右方向变化量和排架立杆垂直度左右方向变化量均很小;试验监测数据表明,经加强后的贝雷架杆件加载后的各项参数满足安全要求,技术方案可应用于塔柱横梁施工,保证升船机塔柱横梁施工安全。     

三峡升船机塔柱混凝土施工测量技术

针对三峡垂直升船机高薄壁塔柱结构混凝土形体及内置埋件施工精度指标要求,对三峡升船机塔柱混凝土及内置埋件施工测量中的平面、高程基准传递及埋件定位测量方法进行了研究。分别将天顶仪投点、电磁波测距及中心带照准标志的圆柱螺帽型定位装置施工测量技术运用于混凝土结构尺寸控制测量以及内置埋件定位测量。通过对实测数据的统计与分析,证明三峡升船机塔柱混凝土施工测量技术方案具有可靠性和可行性。     

三峡升船机液压自升式模板施工技术

三峡升船机塔柱混凝土施工工期紧,精度要求高,为保证施工进度和质量,采用了液压自升式模板。本文重点介绍了三峡升船机塔柱混凝土液压自升式模板施工技术、自升式模板改进措施以及为满足自升式模板上升而在塔柱板梁、牛腿处进行的结构处理措施。实践证明,液压自升式模板施工技术的应用与改进满足了三峡升船机塔柱筒体混凝土的设计要求,有效地提高施工效率、节约了成本,保证了工程质量并提高施工的安全性,可为其他水电工程施工提供借鉴。     

三峡升船机船厢室段混凝土浇筑设备布置研究

本文详细介绍了三峡升船机船厢室段混凝土施工设备的选型过程,包括船厢室段混凝土施工特性分析,投标阶段浇筑设备选型论证,施工阶段对设备选型的系统调整和优化。施工设备的工程实践效果表明,三峡升船机船厢室段混凝土浇筑设备布置方案有效覆盖了所有浇筑面,满足浇筑高峰期混凝土入仓强度的要求,施工进度、成本、安全均得到有效控制。三峡升船机船厢室段混凝土浇筑设备经过前期的合理规划,以及后期的系统调整与优化,对三峡升船机工程的顺利完建发挥了重要作用,具有较高的推广应用价值。     

跨径悬索桥塔下横梁施工技术分析

作为一种特殊桥型,悬索桥因其结构造型美观、经济性能良好及极强适应性在桥梁工程建设中得到了广泛应用。混凝土索塔是悬索桥的主要形式,但因混凝土索塔施工设备进场难度加大,且多以空心变截面塔柱为主,将大大增加模板施工难度。为此,索塔塔下横梁施工已经成为工程建设的关键,研究混凝土索塔横梁施工技术具有重要意义。该文以某大跨径悬索桥工程为例,对其施工工艺进行了探讨,以期有效提升工程质量。     

三峡升船机塔柱混凝土温控防裂技术

三峡升船机塔柱结构复杂,属于高层薄壁结构,混凝土温度受环境温度影响较大,其混凝土温控难度极大。在施工实践中,通过优化混凝土配合比、合理布置混凝土冷却系统、科学调控冷却水温度与通水时间,科学调整外部环境温度、同时引进混凝土养护新材料、新工艺,并且加强对温控的施工管理等措施,保证了塔柱混凝土的施工质量,证明了温控方案的科学合理性。三峡升船机塔柱混凝土温控防裂技术对研究国内外升船机工程温控措施技术水平,提高水电工程混凝土施工质量,节省工程造价等具有重要的参考价值。     

Insertion of triangulated surfaces into a meccano tetrahedral discretization by means of mesh refinement and optimization procedures

In this paper, we present a new method for inserting several triangulated surfaces into an existing tetrahedral mesh generated by the meccano method. The result is a conformal mesh where each inserted surface is approximated by a set of faces of the final tetrahedral mesh. First, the tetrahedral mesh is refined around the inserted surfaces to capture their geometric features. Second, each immersed surface is approximated by a set of faces from the tetrahedral mesh. Third, following a novel approach, the nodes of the approximated surfaces are mapped to the corresponding immersed surface. Fourth, we untangle and smooth the mesh by optimizing a regularized shape distortion measure for tetrahedral elements in which we move all the nodes of the mesh, restricting the movement of the edge and surface nodes along the corresponding entity they belong to. The refining process allows approximating the immersed surface for any initial meccano tetrahedral mesh. Moreover, the proposed projection method avoids computational expensive geometric projections. Finally, the applied simultaneous untangling and smoothing process delivers a high‐quality mesh and ensures that the immersed surfaces are interpolated. Several examples are presented to assess the properties of the proposed method.     

Certification Institutions Expected to Update and Transfer Information on Present Standards

Standards are the basis for production enterprises to organize production, ex-factory inspection, trade (delivery) and technical exchanges, product certification, quality arbitration and supervision.……     

From Industry 4.0 to Research 4.0. Development of High Performance Fibers in the Light of Digitization

We associate a variety of innovations with the term ＂Industry 4.0＂. The pioneer of many 4.0 modifications forms the basisfor the trend towards the integrated di...     

Flow calorimeter for enthalpy increment measurements on condensed gases

A flow calorimeter for enthalpy increment measurements on condensed gases is presented. A better knowledge of the properties of the liquefied natural gas is needed, and therefore a liquid loop has been designed for our flow calorimeter. The fluid loop in the calorimeter is designed in order to avoid the two-phase region, since two phases would give compositional disturbances in the measurements. The avoidance of the two-phase region is made possible by increasing the pressure of the test fluid after the measurement section, then heating the fluid at super-critical pressure past the critical point. Finally, the fluid is throttled to the low-pressure gas state at the inlet condition of the compressor that circulates the fluid. To perform the pressure increase, a new cryogenic pump has been designed. To evaluate the new equipment, measurements were taken on liquid ethane over the temperature range 146–256 K at pressure between 0.9 and 5.1 MPa.     

Refrigerators Enter a New Era of Health Preservation Frestech initiates the establishment of China's first standard for household sterilization refrigerators

On November 30, 2007, the China Association for Standardization (CAS) held a press conference at Beijing Diaoyutai State Guest House. Leaders from the China Household Electric Appliance Research Institute, the China Household Electric Appliance Association, and the China Consumers' Association attended and made speeches.……     

Roman iron and steel: A review

ABSTRACT

The production of ferrous metal increased during the Roman Late Republican period, Principate and Empire. The direct bloomery process was used to extract the metal from its ores using slag-tapping and slag-pit furnaces. The fuel was charcoal and an air blast was introduced by bellows-operated tuyères. Iron formed as a bloom, often as a spongy mass of metal, which contained impurities from the smelting process, including unreacted ore, fuel, slag and fragments from the furnace walls, while the metal was often inhomogeneous with varied carbon contents. Blooms were either smithed directly into bars or ingots or they were broken up, which also allowed the removal of gross impurities and a selection of pieces with similar properties to be made. These could then be forge-welded together and formed into characteristically shaped ingots. Making steel in the furnace seems to have been achieved: it depended on the ore and the furnace and conditions within it. Surface carburization was also carried out. Iron and steel were used extensively in construction and for tools and weapons. Fire welding was often used to add pieces of steel to make the edges of tools and weapons, which could be heat-treated by quenching to harden them.     

Optimum-Simulation von Ernteprozessen

Zusammenfassung Bei der Gestaltung von Ernteprozessen — beispielsweise des Prozesses Mähdrusch, Körnertransport und -abnahme — als transportverbundene Fließarbeitsverfahren mit mindestens zwei verschiedenen Arbeitsmitteln gibt es einen großen Optimierungsspielraum. Solche Prozesse sind mehrstufige Bedienungsprozesse mit gemischter Anordnung der Bedienungseinrichtungen. Außerdem besitzen sie stark ausgeprägte räumliche Aspekte. Es wird vor allem gezeigt, welche Merkmale solcher Prozesse in Simulationsmodellen abgebildet sein müssen, welche Zielgrößen in Abhängigkeit von welchen Einflußgrößen unter Berücksichtigung welcher Prozeßbedingungen ermittelt werden sollten und wie der Bewertungsprozeß zur Ermittlung der gewünschten Informationen gestaltet werden muß.     

A study of centrifugal cast high boron high speed steel

In the present study a high‐boron high speed steel (HSS) roll material was designed. Many expensive alloy elements have been substituted by cheap boron alloy, and high‐boron high speed steel roll has been manufactured by centrifugal casting method. The microstructures, mechanical properties and wear resistance of centrifugal casting high‐boron high speed steel roll have been investigated by optical microscopy (OM), scanning electron microscopy (SEM), and X‐ray diffraction (XRD) analysis, hardness test, impact test and wear test. The results indicated that the solidification microstructures of high‐boron high speed steel roll consisted of M₂(B,C), (W,Mo)₂(B,C), M₃(B,C), M₂₃(B,C)₆ type borocarbides and martensite, a small amount of retained austenite. Borocarbides were continuously distributed over the grain boundary. After quenching from 1050 °C, local broken network appeared in partial borocarbides, and fine secondary borocarbide precipitated from the matrix. After tempering from 525 °C, the amount of precipitated borocarbide increased significantly. After heat treatment, the hardness of high‐boron high speed steel roll excelled 60 HRC, and its impact toughness excelled 8.0 J/cm². The single groove steel rolling amount of high‐boron high speed steel rolls increases by 500% than that of bainite cast iron roll, when the rolls are used in K₁ mill housing of bar mill.     

Thixotropy of Systems with Shear Thinning and Plastic Flow Behavior

The definition of the thixotropy is a decrease in viscosity with time in shear and a subsequent recovery of viscosity after the shear deformation is removed.We ...